In the early 1990s, the younger half of the billionaire Koch brothers, David Koch, was involved in a plane crash on a runway at Los Angeles International Airport. He survived, but when he was being treated for his injuries, a doctor discovered that Koch had prostate cancer.

This inspired Koch, and as he puts it: “Once you get that disease. . . you become a crusader to try to cure the disease not only for yourself but for other people.”

Of course, David Koch knows a thing or two about crusading. Along with his brother Charles, he's been deeply engaged in political activism for over thirty years, promoting a libertarian set of views. Right now, the brothers are engaged in a massive push to win Republican control of the U.S. Senate.

What's less well known is that Koch has also put some serious money behind cancer research, with his donations in this area likely exceeding his giving to such policy think tanks as Cato and Reason.

Tracking the full scope of Koch's health giving is tricky, since not all of that giving flows through his foundation. Some some of it has been done through that charitable outfit, and some of it individually or with his wife Julia. What is clearer is that the overall scope of his health giving has been huge.

Koch has a deep background in the sciences. He has undergraduate and graduate degrees in chemical engineering, and was a research and process design engineer for several companies before joining his father's fossil fuels conglomerate Koch Industries, where he's now executive vice president.

Some of Koch's other gifts to cancer research include: $20 million to Johns Hopkins University to establish the David H. Koch Cancer Research Center, $66.7 million to Memorial Sloan Kettering Cancer Center, where he's a member of the board of trustees and at least $1 million to MD Anderson Cancer Center in Texas in 2013 where Koch has received much of his own cancer treatment.

Apart from cancer research, Koch has also been involved with the massive $2 billion capital campaign at New York-Presbyterian where he recently pledged $100 million to support the construction of a new ambulatory care center at the hospital's Upper East Side location on York Avenue between 68th and 69th Streets.

Koch gave $26.2 million to the Hospital for Special Surgery in New York City where he sits on the board of trustees. He and his wife Julia recently pledged $10 million to the Jaffe Food Allergy Institute at Mount Sinai Medical Center. The allergy center will be named the David H.and Julia Koch Research Program in Food Allergy Therapeutics.

It's important to point out that many of Koch's biggest cancer gifts happened last decade or prior. However, with the personal stakes that Koch has here, expect health, particularly cancer research, to remain a top priority. Each Koch brother has more than $40 billion and we're betting much of it goes toward philanthropy.

One last note: In the political arena, the Koch brothers have spent millions to torpedo the Affordable Care Act, an effort that—among other things—has helped to block expansion of Medicaid to low-income Americans in a number of states. David Koch's private health giving is all the more striking in light of that push to thwart an expansion of public health coverage.